A device and method for evaluating the effect of concrete protective coating under concentrated infiltration channel on resisting external water pressure

Abstract

The present invention discloses a device and method for evaluating the effect of concrete protective coating against external water pressure under concentrated infiltration channel, the device includes a concrete specimen, a water injection assembly, a specimen container, a wave spring, a pressure sensor and a control device; the concrete specimen is installed in the specimen container through a sleeve, the upper surface is covered with a protective coating, a concentrated infiltration channel is prefabricated in the concrete specimen, and a water permeable channel is arranged at the bottom of the specimen container; the water injection assembly is used to inject water into the infiltration channel through the water permeable channel, the wave spring is above the protective coating, the upper end is fixedly connected to the pressure sensor, and the lower end touches the upper surface of the protective coating without deformation; the control device is respectively connected to the pressure sensor and the water injection assembly. The present invention can evaluate the effect of the protective coating against external water pressure by measuring the stress and displacement of the entire surface under the action of external water pressure, the test is convenient, the measurement result is accurate, and the shortcomings of the concrete protective coating in the evaluation of the effect of resisting external water pressure are made up.

Description

Technical Field

[0001] The invention belongs to the technical field of water conservancy engineering structure detection, and specifically relates to a device and method for evaluating the effect of concrete protective coating under a concentrated infiltration channel on resisting external water pressure. Background Art

[0002] With the completion of the construction of large-scale water conservancy projects (dams, long-distance water transfer projects, etc.) in my country, the current focus is on their operation and maintenance to ensure their safe and efficient operation. The main material used in these water conservancy projects is concrete. Under the long-term scouring of water flow and backwater pressure, concrete will suffer from surface peeling, through cracks and other diseases. If not repaired in time, they will continue to expand and cause structural collapse.

[0003] A common method for repairing concrete in water conservancy projects is to apply protective material coatings on the damaged surface of the concrete, such as various organic and inorganic coatings such as polyurethane, polyurea, and epoxy resin. These coatings form a bond with the concrete after solidification and hardening to protect the concrete from erosion. However, in some projects, the concrete protective coating not only needs good bonding properties, but also needs to have a certain ability to resist external water pressure. For example, the concrete structure at the bottom of a 200-meter-high dam will be subjected to a water pressure of up to 2Mpa. If the concrete surface is protected, the back of the concrete structure will be subjected to a water pressure of 2MPa. The concrete surface protective material may fail under this water pressure. How to evaluate the anti-external water pressure effect of the concrete protective coating is lacking in current research. Summary of the invention

[0004] The purpose of the present invention is to address the above shortcomings and provide a device and method for evaluating the external water pressure resistance of concrete protective coatings under concentrated infiltration channels. The device can evaluate the external water pressure resistance of the protective coating by measuring the stress and displacement of the entire surface under the action of external water pressure. It has the advantages of convenient testing and accurate measurement results, and makes up for the shortcomings of concrete protective coatings in evaluating the external water pressure resistance effect.

[0005] To achieve the above object, the present invention is implemented by the following technical solutions:

[0006] A device for evaluating the effect of concrete protective coating against external water pressure under concentrated infiltration channel, comprising a concrete specimen, a water injection assembly, a specimen container, a wave spring, a pressure sensor and a control device;

[0007] The concrete specimen is installed in the specimen container through a sleeve, the upper surfaces of the concrete specimen and the sleeve are covered with a protective coating, a concentrated infiltration channel is prefabricated in the concrete specimen, and a water permeable channel corresponding to the infiltration channel of the concrete specimen is provided at the bottom of the specimen container;

[0008] The water injection assembly is used to inject water into the permeation channel through the water permeable channel; a plurality of wave springs are arranged at intervals above the protective coating, the upper end of the wave spring is fixedly connected to the pressure sensor, and the lower end touches the upper surface of the protective coating without deformation;

[0009] The control device is respectively connected to the pressure sensor and the water injection assembly to control the water injection pressure, and collects the pressure transmitted by the wave spring through the pressure sensor.

[0010] Furthermore, the cross-section of the concentrated permeation channel is circular, linear or cross-shaped.

[0011] Furthermore, the outer side of the sleeve and the inner wall of the specimen container are both provided with threads, and the two are connected by threads; the inner side of the sleeve is also provided with threads, and the concrete specimen is cast and cured in the sleeve, and the inner thread of the sleeve is used to ensure tight adhesion with the formed concrete to clamp the concrete specimen and prevent it from falling out under the water pressure. Preferably, the sleeve can be composed of two halves, which can be assembled and disassembled, and is easy to take out. After the concrete specimen is formed and the concentrated infiltration channel is made, the protective coating is covered on the surface of the concrete specimen and the sleeve, with a thickness of 1.5 mm, a flat surface, and a uniform interior.

[0012] Furthermore, a sleeve cover plate for compressing the protective coating is provided on the top of the sleeve, and the sleeve cover plate is connected to the sleeve by bolts.

[0013] Furthermore, the pressure sensor is a multi-point thin film pressure sensor, the upper end of the wave spring is bonded to the pressure sensor via a mounting pad, the mounting pad can cover the upper surface of the wave spring, and the mounting pad can be a round cardboard.

[0014] Furthermore, the upper part of the pressure sensor is connected to a smooth wooden board by bonding, and the wooden board is connected to a bracket and horizontally supported in the air by the bracket. The position of the wooden board is adjusted by the bracket so that the lower end of the wave spring steel spring just touches the upper surface of the protective coating without deformation.

[0015] Furthermore, the water injection assembly includes a water pump, a pressure gauge, a water storage tank and a water pipe; the water pump is connected to a control device, and the control device controls the step-by-step pressurization; the pressure gauge is connected to the water pump to display the water pressure at each moment, the inlet of the water pump is connected to the water storage tank, and the outlet of the water pump is connected to the water permeable channel through the water pipe.

[0016] The present invention also provides a method for evaluating the effect of concrete protective coating on resisting external water pressure under concentrated infiltration channel, based on the above-mentioned device for evaluating the effect of concrete protective coating on resisting external water pressure under concentrated infiltration channel, comprising the following steps:

[0017] The water injection component is controlled by the control device to pressurize step by step from zero, and the increment of each pressurization and the time to maintain the pressure are set. The increment of each pressurization can be set to 0.05Mpa, and the pressure can be maintained for 2 hours; if the protective coating does not leak or be damaged, continue to increase the pressure step by step until the protective coating is damaged;

[0018] The force F of each wave spring at time t is recorded by the control device it , and take photos to record the damage morphology of the protective coating;

[0019] The data obtained in the above steps are processed and analyzed to obtain relevant parameters of protective coating damage, and the effect of concrete protective coating on resisting external water pressure under concentrated infiltration channels is comprehensively evaluated.

[0020] Preferably, before the test begins, the preparation and installation steps of the device include:

[0021] Step 1: pouring a concrete specimen in a sleeve, inserting a prefabricated circular, linear or cross-shaped prefabricated sheet that runs through the bottom to the top of the concrete specimen during the concrete pouring process; when the concrete is initially set, the prefabricated sheet is pulled out to form a prefabricated concentrated infiltration channel;

[0022] Step 2: Curing the prefabricated concrete specimens with concentrated infiltration channels of different shapes in the sleeve to the standard age; screwing the sleeve into the specimen container with the inner screw and tightening it;

[0023] Step 3: Apply the protective coating material evenly and evenly on the upper surface of the concrete specimen with a thickness of 1.5 mm; cover the sleeve cover plate on the sleeve, press the outer edge of the circular protective coating, and tighten the bolts connecting the sleeve cover plate and the sleeve;

[0024] Step 4: Assemble the device and adjust the horizontal height of the multi-point film pressure sensor through the bracket so that the lower end of the wave spring steel spring bonded at the lower end just touches the upper surface of the protective coating without deformation.

[0025] Preferably, the relevant parameters of the protective coating damage include the external water pressure P when the protective coating is damaged, the maximum destructive force Tmax of the protective coating, and the damage displacement S of the protective coating. max The failure modes of protective coatings under different crack forms are obtained by the following methods:

[0026] By recording the step-by-step pressurization process of the water injection assembly, an external water pressure-time curve is obtained on the control device, and the external water pressure P when the protective coating is destroyed is obtained from the external water pressure-time curve according to the time when the protective coating is destroyed;

[0027] The force F of each wave spring at time t is obtained through the reflection of the pressure sensor on the control device. it, and obtain the force T of the external water pressure on each point on the protective coating at time t it =F it , draw a cloud diagram of the forces at each point on the protective coating at the time of destruction, and obtain the maximum destructive force T generated by the protective coating at the time of destruction max ;

[0028] According to the elastic modulus E of the wave spring, calculate the deformation S' of each wave spring steel spring at time t it , which is approximately equal to the deformation S of the protective coating at that point it =S' it , draw a cloud diagram of the displacement of each point on the protective coating at the time of destruction, and obtain the maximum displacement S generated on the surface when the protective coating is destroyed max ; Among them, S' it =F it ×E;

[0029] By observing the damage morphology of the protective coating recorded by photograph, the damage mode of the protective coating under different crack forms is analyzed. Depending on the type of protective coating used and the form of cracks, the damage mode formed is also different, and center penetration damage, center bulging damage, edge splitting damage, etc. may occur.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The device and method described in the present invention can measure the time-varying characteristics of the stress and displacement on the surface of the protective coating under the external water pressure of the concentrated infiltration channel, and evaluate its resistance to external water pressure through the stress and displacement conditions. It has the advantages of convenient testing and accurate measurement results, and makes up for the shortcomings of concrete protective coating in the evaluation of the resistance to external water pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of the structure of a device for evaluating the effect of concrete protective coatings under concentrated infiltration channels on resisting external water pressure provided by Example 1 of the present invention;

[0033] Figure 2 This is a schematic structural diagram of the circular hole-shaped concentrated permeation channel described in Example 1;

[0034] Figure 3 This is a schematic structural diagram of the linear concentrated permeation channel described in Example 1;

[0035] Figure 4 This is a schematic structural diagram of the cross-shaped concentrated permeation channel described in Example 1;

[0036] Figure 5 This is a schematic diagram of the bolt connection between the sleeve cover plate and the sleeve described in Example 1;

[0037] Figure 6 Schematic diagram of the distribution arrangement of the wave spring described in Example 1 on the multi-point diaphragm pressure sensor.

[0038] 1. Concrete specimen; 2. Sleeve; 3. Centralized infiltration channel; 4. Specimen container; 41. Bottom plate; 5. Water-permeable channel; 6. Protective coating; 7. Water injection assembly; 71. Water pump; 72. Pressure gauge; 73. Water storage tank; 74. Water guide pipe; 8. Wave spring; 9. Multi-point diaphragm pressure sensor; 10. Computer; 11. Bracket; 12. Sleeve cover; 13. Wooden board. DETAILED DESCRIPTION

[0039] The preferred embodiments of the present invention will be described in more detail below in conjunction with the accompanying drawings and specific examples.

[0040] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0041] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0042] Example 1

[0043] like Figure 1 The device shown is for evaluating the effect of concrete protective coating against external water pressure under concentrated infiltration channel, comprising concrete specimen 1, sleeve 2, concentrated infiltration channel 3, specimen container 4, bottom plate 41, protective coating 6, water injection assembly 7, wave spring 8, multi-point membrane pressure sensor 9, computer 10 (control device), bracket 11 and sleeve cover plate 12.

[0044] The concrete specimen 1 is prefabricated with a concentrated infiltration channel 3, which is substantially perpendicular to the upper and lower surfaces of the concrete specimen 1, and its cross section can be circular, linear or cross-shaped, such as Figures 2 to 4 As shown. The concrete specimen 1 is cast and cured in a sleeve 2 with bidirectional threads (threads are provided on both the inner and outer sides). The inside of the sleeve 2 is tightly bonded to the concrete specimen 1 through the inner threads, and the outside of the sleeve 2 is screwed to the inner wall of the specimen container 4 through the threads. The sleeve cover 12 is placed on the sleeve 2 and connected to the sleeve 2 through a number of bolts to compress the outer ring of the protective coating 6, as shown in FIG. Figure 5 As shown. The bottom plate 41 of the specimen container 4 has a circular hole-type water permeable channel 5, which is connected to the concentrated infiltration channel 3 at the top and tightly connected to the water guide pipe 74 in the water injection assembly 7 at the bottom. The protective coating 6 has a thickness of 1.5 mm and is evenly and evenly applied on the upper surface of the concrete specimen 1 and the sleeve 2, and ensures that the outer edge is tightly fitted to the upper surface of the sleeve 2.

[0045] The water injection assembly 7 includes a water pump 71, a pressure gauge 72, a water storage tank 73 and a water pipe 74, wherein the water pump 71 is connected to the control device computer 10 to realize automatic control and adopt a step-by-step pressurization method; the pressure gauge 72 is connected to the water pump 71 to display the water pressure at each moment; the inlet of the water pump 71 is connected to the water storage tank 73 through the water pipe 74, and the outlet is connected to the permeable channel 5 through the water pipe 74.

[0046] The wave spring 8 has a plurality of strips, and the diameter of the cross section is 1 cm. The upper and lower ends are flattened, and the upper end is tightly bonded to the multi-point film pressure sensor 9 through a circular cardboard; the lower end just touches the upper surface of the protective coating 6 without deformation. A plurality of wave springs 8 are spread over the upper surface of the protective coating 6 at a certain distance from each other, such as Figure 6 shown.

[0047] The upper part of the multi-point film pressure sensor 9 is bonded to a smooth wooden board 13, and the wooden board 13 is horizontally supported in the air by a bracket 11. The position of the wooden board 13 is adjusted by the bracket 11 so that the lower end of the wave spring 8 just touches the upper surface of the protective coating 6 without deformation. Figure 1 The multi-point film pressure sensor 9 is connected to the computer 10 via a data line.

[0048] Example 2

[0049] This embodiment provides a method for evaluating the effect of concrete protective coating on resisting external water pressure under concentrated infiltration channel, which is based on the device for evaluating the effect of concrete protective coating on resisting external water pressure under concentrated infiltration channel described in Example 1. In order to further use the device for evaluating the effect of concrete protective coating on resisting external water pressure under concentrated infiltration channel, the following describes the test, recording and analysis methods using the device:

[0050] Step 1: pouring a concrete specimen 1 in a sleeve 2, inserting a prefabricated circular, square or cross-shaped prefabricated sheet that runs through the bottom to the top of the concrete specimen during the concrete pouring process; when the concrete is initially set, the prefabricated sheet is pulled out to form a prefabricated concentrated infiltration channel 3;

[0051] Step 2: Curing the concrete specimen 1 with the prefabricated concentrated infiltration channel 3 in the sleeve 2 to the standard age; screwing the sleeve 2 into the specimen container 4 with an inner screw and tightening it;

[0052] Step 3: Apply the protective coating 6 material evenly and evenly on the upper surface of the concrete specimen 1 with a thickness of 1.5 mm; cover the sleeve cover plate 12 on the sleeve 2, press the outer edge of the circular protective coating 6, and tighten the bolts connecting the sleeve cover plate 12 and the sleeve 2;

[0053] Step 4: Assemble the device, and adjust the horizontal height of the multi-point film pressure sensor 9 through the bracket 11, so that the lower end of the wave spring 8 bonded at the lower end just touches the upper surface of the protective coating 6 without deformation;

[0054] Step 5, start the computer 10; start the water pump 71, and automatically control the water pump 71 to increase the pressure step by step over time through the computer 10, starting from zero, with each pressurization increment of 0.05Mpa, and maintain the pressure for 2 hours; if the protective coating 6 does not leak or break, continue to increase the pressure step by step until the protective coating 6 is broken, and record the pressure when the protective coating 6 is broken;

[0055] Step 6: Use the computer 10 to record the force F of the i-th wave spring 8 at time t it , and taking photos to record the damage morphology of the protective coating 6 when it is damaged;

[0056] Step 7: Analyze the data obtained in step 6, including:

[0057] (1) Analyze and obtain the external water pressure P when the protective coating 6 is destroyed: record the step-by-step pressurization process of the water pump 71, obtain the external water pressure-time curve on the computer 10, and record the external water pressure P corresponding to the destruction of the protective coating 6.

[0058] (2) The maximum destructive force T of the protective coating 6 is obtained by analysis max: The force F of each wave spring steel spring at time t is obtained by the reflection of the multi-point film pressure sensor 9 on the computer 10 it , we can get the force T of the external water pressure on each point on the protective coating 6 at time t it =F it , draw a cloud diagram of the forces at each point on the protective coating 6 at the time of destruction, and obtain the maximum destructive force T_max generated by the protective coating 6 at the time of destruction;

[0059] (3) Analysis of the damage displacement S of the protective coating 6 max : The elastic modulus E of the wave spring 8 is known, and the formula S' is used by a computer it =F it ×E calculates the deformation S' of the i-th wave spring 8 at time t it , which is approximately equal to the deformation S of the protective coating 6 at this point it =S' it , draw a cloud diagram of the displacement of each point on the protective coating 6 at the time of destruction, and at the same time obtain the maximum displacement S of the surface when the protective coating 6 is destroyed max ;

[0060] (4) observing the damage morphology of the protective coating 6 recorded by photographing, and analyzing the damage modes of the protective coating 6 under different crack forms (circular, linear, cross);

[0061] (5) External water pressure P and maximum destructive force T corresponding to the destruction of the protective coating 6 max and the maximum displacement S max As well as the failure mode, the effect of concrete protective coating on resisting external water pressure under concentrated infiltration channels is comprehensively evaluated.

[0062] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Without departing from the scope and technical principles of the described embodiments, many modifications and changes are obvious to those of ordinary skill in the art, and these modifications and changes should also be regarded as the scope of protection of the present invention.

Claims

1. A device for evaluating the effect of concrete protective coating against external water pressure under concentrated infiltration channel, characterized in that: It includes concrete specimen, water injection assembly, specimen container, wave spring, pressure sensor and control equipment; The concrete specimen is installed in the specimen container through a sleeve, the upper surfaces of the concrete specimen and the sleeve are covered with a protective coating, a concentrated infiltration channel is prefabricated in the concrete specimen, and a water permeable channel corresponding to the infiltration channel of the concrete specimen is provided at the bottom of the specimen container; The water injection assembly is used to inject water into the permeation channel through the water permeable channel; The wave springs are arranged at intervals above the protective coating, the upper end of the wave spring is fixedly connected to the pressure sensor, and the lower end touches the upper surface of the protective coating without deformation; The control device is respectively connected to the pressure sensor and the water injection assembly to control the water injection pressure, and collects the pressure transmitted by the wave spring through the pressure sensor; The device is used to implement a method for evaluating the effect of concrete protective coating against external water pressure under a concentrated infiltration channel, and the method comprises the following steps: The water injection component is controlled by the control device to pressurize step by step from zero, and the increment of each pressurization and the time to maintain the pressure are set; if the protective coating is not damaged by water leakage, the pressure is continued to be increased step by step until the protective coating is damaged; The force of each wave spring at time t is recorded by the control device F it , and take photos to record the damage morphology of the protective coating; The data obtained in the above steps are processed and analyzed to obtain relevant parameters of protective coating damage, which are used to comprehensively evaluate the effect of concrete protective coating on resisting external water pressure under concentrated infiltration channels; The relevant parameters of the protective coating damage are obtained by the following method: By recording the step-by-step pressurization process of the water injection assembly, an external water pressure-time curve is obtained on the control device, and the external water pressure P when the protective coating is destroyed is obtained from the external water pressure-time curve according to the time when the protective coating is destroyed; The force of each wave spring at time t is obtained through the reflection of the pressure sensor on the control device. F it , and obtain the force of the external water pressure on each point on the protective coating at time t T it = F it , draw a cloud diagram of the forces at each point on the protective coating at the moment of destruction, and obtain the maximum destructive force generated by the protective coating at the time of destruction T max ; According to the elastic modulus E of the wave spring, calculate the deformation of each wave spring steel spring at time t S’ it , which is approximately equal to the deformation of the protective coating at that point S it = S’ it , draw a cloud diagram of the displacement of each point on the protective coating at the time of destruction, and obtain the maximum displacement of the surface when the protective coating is destroyed ;in, S’ it = F it ×E; By observing the damage morphology of the protective coating recorded by photograph, the damage mode of the protective coating under different crack forms is analyzed.

2. The device for evaluating the effect of concrete protective coating against external water pressure under concentrated infiltration channel according to claim 1 is characterized in that: The cross section of the concentrated permeation channel is circular, linear or cross-shaped.

3. The device for evaluating the effect of concrete protective coating against external water pressure under concentrated infiltration channel according to claim 1, characterized in that: The outer side of the sleeve and the inner wall of the specimen container are both provided with threads, and the two are connected by threads; the inner side of the sleeve is also provided with threads.

4. The device for evaluating the effect of concrete protective coating against external water pressure under concentrated infiltration channel according to claim 1, characterized in that: A sleeve cover plate for compressing the protective coating is provided on the top of the sleeve, and the sleeve cover plate is connected to the sleeve by bolts.

5. The device for evaluating the effect of concrete protective coating against external water pressure under concentrated infiltration channel according to claim 1, characterized in that: The pressure sensor is a multi-point thin film pressure sensor, and the upper end of the wave spring is bonded to the pressure sensor via a mounting pad, and the mounting pad can cover the upper surface of the wave spring.

6. The device for evaluating the effect of concrete protective coating against external water pressure under concentrated infiltration channel according to claim 1, characterized in that: The upper part of the pressure sensor is connected to the wooden board, and the wooden board is connected to the bracket.

7. The device for evaluating the effect of concrete protective coating against external water pressure under concentrated infiltration channel according to claim 1, characterized in that: The water injection assembly includes a water pump and a water storage tank; the water pump is connected to a control device, and the control device controls the water pump to increase pressure step by step; the inlet of the water pump is connected to the water storage tank, and the outlet of the water pump is connected to a water permeable channel.

8. A method for evaluating the effect of concrete protective coating against external water pressure under concentrated infiltration channel, characterized in that: The device for evaluating the effect of concrete protective coating against external water pressure under concentrated infiltration channel according to any one of claims 1 to 7 comprises the following steps: The water injection component is controlled by the control device to pressurize step by step from zero, and the increment of each pressurization and the time to maintain the pressure are set; if the protective coating is not damaged by water leakage, the pressure is continued to be increased step by step until the protective coating is damaged; The force of each wave spring at time t is recorded by the control device F it , and take photos to record the damage morphology of the protective coating; The data obtained in the above steps are processed and analyzed to obtain relevant parameters of protective coating damage, which are used to comprehensively evaluate the effect of concrete protective coating on resisting external water pressure under concentrated infiltration channels; The relevant parameters of the protective coating damage are obtained by the following method: By recording the step-by-step pressurization process of the water injection assembly, an external water pressure-time curve is obtained on the control device, and the external water pressure P when the protective coating is destroyed is obtained from the external water pressure-time curve according to the time when the protective coating is destroyed; The force of each wave spring at time t is obtained through the reflection of the pressure sensor on the control device. F it , and obtain the force of the external water pressure on each point on the protective coating at time t T it = F it , draw a cloud diagram of the forces at each point on the protective coating at the moment of destruction, and obtain the maximum destructive force generated by the protective coating at the time of destruction T max ; According to the elastic modulus E of the wave spring, calculate the deformation of each wave spring steel spring at time t S’ it , which is approximately equal to the deformation of the protective coating at that point S it = S’ it , draw a cloud diagram of the displacement of each point on the protective coating at the time of destruction, and obtain the maximum displacement of the surface when the protective coating is destroyed ;in, S’ it = F it ×E; By observing the damage morphology of the protective coating recorded by photograph, the damage mode of the protective coating under different crack forms is analyzed.

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